Field of the Invention
The subject matter of this specification is in the field of lateral flow assay strips and related methods.
Background of the Invention
Lateral flow assay tests, also known as a lateral flow immunoassay test or a lateral flow immunochromatography assay test, detect the presence or absence of an analyte in a sample. Lateral flow tests are used for a variety of diagnostic tests, such as a pregnancy test. In general, a lateral flow assay strip contains a collection pad, a sample pad, a conjugate pad, a reaction membrane, and a wick or waste container. The collection pad collects the sample. The sample pad is an absorbent pad that absorbs the test sample. The sample pad is also pre-loaded with chemicals that “pre-condition” the samples so that they are suitable for reaction conditions when they travel downstream. The conjugate pad contains specific antibodies (or antigens) that are conjugated to nanoparticles (tracers), which are commonly conidial gold, and correspond with a specific target analyte in order to ensure a chemical reaction between the target analyte and its antibody. A reaction membrane is where the anti-target analyte antibodies (or protein-conjugated target analytes) are immobilized in a line that crosses the membrane to act as a capture zone or test line. A wick is an absorbent pad that collects the sample that has traveled through the reaction zones.
Once a sample is collected, the lateral flow of the sample is initiated by capillary action so that the sample passes through the conjugate pad and reaction membrane.
Current lateral flow assay strips only have one sample pad, so a specimen will move from the sample pad and enter one side of the conjugate pad before eventually flowing to the reaction membrane. This method is effective, but there are other methods to achieve increased sensitivity. U.S. Pat. No. 6,248,598 by Bogema provides an immunoassay that may collect saliva and test multiple analytes, however, Bogema does not allow for multiple specimen loading points on both sides of a conjugate pad, which results in increased sensitivity of results. Thus, there is a need to increase the sensitivity of the test results for lateral assay strips by increasing the number and locations of sample pads in relation to the conjugate pad.